Thread: Problem compiling StringUtils.class

Hi, I have decompile and recompile a jar file to modify the class StringUtils.class. Once I modified it and recompile is giving me problems during run.
When I compare the original function list to that I have recompile, there is a public function that is not present in the original. I am using "javac -cp guevana-20.0.jar StringUtils.java" to compile.

The javap results are the following:

//original
public final class com.google.appinventor.common.utils.StringUtils {
public static final com.google.common.base.CharMatcher VALID_FILENAME_CHARS;
public static java.lang.String quote(java.lang.String);
public static java.lang.String unquote(java.lang.String);
public static java.lang.String escape(java.lang.String);
public static boolean contains(java.lang.String[], java.lang.String);
public static java.lang.String join(java.lang.String, java.lang.String[]);
public static java.lang.String join(java.lang.String, java.lang.Iterable<java.lang.String>);
public static void join(java.lang.StringBuilder, java.lang.String, java.lang.String...);
public static java.lang.String userToPackageName(java.lang.String);
public static java.lang.String getProjectPackage(java.lang.String, java.lang.String);
public static java.lang.String getQualifiedFormName(java.lang.String, java.lang.String);
public static java.lang.String replaceLastOccurrence(java.lang.String, java.lang.String, java.lang.String);
public static java.lang.String createProjectName(java.util.Set<java.lang.String>) ;
public static java.lang.String normalizeForFilename(java.lang.String);
public static java.lang.String toJson(java.lang.String);
public static int countMatches(java.lang.String, java.lang.String);
public static boolean isNullOrEmpty(java.lang.String);
static {};
}

//my compilation

public final class com.google.appinventor.common.utils.StringUtils {
public static final com.google.common.base.CharMatcher VALID_FILENAME_CHARS;
public com.google.appinventor.common.utils.StringUtils();
public static java.lang.String quote(java.lang.String);
public static java.lang.String unquote(java.lang.String);
public static java.lang.String escape(java.lang.String);
public static boolean contains(java.lang.String[], java.lang.String);
public static java.lang.String join(java.lang.String, java.lang.String[]);
public static java.lang.String join(java.lang.String, java.lang.Iterable<java.lang.String>);
public static void join(java.lang.StringBuilder, java.lang.String, java.lang.String...);
public static java.lang.String userToPackageName(java.lang.String);
public static java.lang.String getProjectPackage(java.lang.String, java.lang.String);
public static java.lang.String getQualifiedFormName(java.lang.String, java.lang.String);
public static java.lang.String replaceLastOccurrence(java.lang.String, java.lang.String, java.lang.String);
public static java.lang.String createProjectName(java.util.Set<java.lang.String>) ;
public static java.lang.String normalizeForFilename(java.lang.String);
public static java.lang.String toJson(java.lang.String);
public static int countMatches(java.lang.String, java.lang.String);
public static boolean isNullOrEmpty(java.lang.String);
static {};
}

public final class com.google.appinventor.common.utils.StringUtils {
public static final com.google.common.base.CharMatcher VALID_FILENAME_CHARS;
public com.google.appinventor.common.utils.StringUtils();
public static java.lang.String quote(java.lang.String);
public static java.lang.String unquote(java.lang.String);
public static java.lang.String escape(java.lang.String);
public static boolean contains(java.lang.String[], java.lang.String);
public static java.lang.String join(java.lang.String, java.lang.String[]);
public static java.lang.String join(java.lang.String, java.lang.Iterable<java.lang.String>);
public static void join(java.lang.StringBuilder, java.lang.String, java.lang.String...);
public static java.lang.String userToPackageName(java.lang.String);
public static java.lang.String getProjectPackage(java.lang.String, java.lang.String);
public static java.lang.String getQualifiedFormName(java.lang.String, java.lang.String);
public static java.lang.String replaceLastOccurrence(java.lang.String, java.lang.String, java.lang.String);
public static java.lang.String createProjectName(java.util.Set<java.lang.String>) ;
public static java.lang.String normalizeForFilename(java.lang.String);
public static java.lang.String toJson(java.lang.String);
public static int countMatches(java.lang.String, java.lang.String);
public static boolean isNullOrEmpty(java.lang.String);
static {};
}



Question:
How can I get rid of the "public com.google.appinventor.common.utils.StringUtils(); " public function that appears on my compiled file?

Originally Posted by Norm

Sorry, I do not understand what the problem is when the code is executed.
Can you copy the full text of the error messages from when the code is executed?


Looks like a constructor for the class

This is the error message once the whole program is run. The StringUtils.class is in the package com.google.appinventor.common.utils, in a file called CommonUtils.jar.
I can not figure out why the original CommonUtils,jar works, and my compilation does not.

Dec 27, 2022 10:51:07 PM com.google.appinventor.buildserver.BuildServer$1 run
INFO: BUILD 1 FINISHED
Exception in thread "Thread-3" java.lang.NoClassDefFoundError: com/google/appinventor/common/utils/StringUtils
at com.google.appinventor.buildserver.ProjectBuilder. processCompilerOutput(ProjectBuilder.java:463)
at com.google.appinventor.buildserver.ProjectBuilder. build(ProjectBuilder.java:184)
at com.google.appinventor.buildserver.BuildServer.bui ld(BuildServer.java:734)
at com.google.appinventor.buildserver.BuildServer.bui ldAndCreateZip(BuildServer.java:689)
at com.google.appinventor.buildserver.BuildServer.acc ess$300(BuildServer.java:74)
at com.google.appinventor.buildserver.BuildServer$1.r un(BuildServer.java:625)
at com.google.appinventor.buildserver.NonQueuingExecu tor$1.run(NonQueuingExecutor.java:52)
at java.lang.Thread.run(Thread.java:750)
Caused by: java.lang.ClassNotFoundException: com.google.appinventor.common.utils.StringUtils
at java.net.URLClassLoader.findClass(URLClassLoader.j ava:387)
at java.lang.ClassLoader.loadClass(ClassLoader.java:4 18)
at sun.misc.Launcher$AppClassLoader.loadClass(Launche r.java:352)
at java.lang.ClassLoader.loadClass(ClassLoader.java:3 51)
... 8 more

Originally Posted by Norm

Look in your jar file to see what it contains. You can use any zip utility program to open it. Rename to .zip if needed.
See if the StringUtils.class file is on the path: com/google/appinventor/common/utils/

Thanks for your answer. I do that already. I think I did not provide sufficient information.
There is a whole suite called app inventor. Inside the suite, there is one JAR file called CommonUtils.jar.
When I unzip it, there is three CLASS files. One of those three CLASS files is StringUtils.class.
I decompile it from StringUtils.class to STringUtils.java. I then modify one constant and recompile and repackage into a new JAR.
Once I run it, I get an error message. In theory, I should not get any error since I am just modifying a String constant, and no method is added nor modified.

When trying to figure out why I get the error message, I noticed that there is a single difference in the
methods from the original compared to the one I compiled, and that difference is an extra method in my compilation that has the same name as the CLASS.
The original jar and classes were compiled with Ant and the one I am compiling is with javac.

Does anybody know any possible cause for this problem, such as:
1. Using javac vs Ant for compilation.
2. Am I missing any argument when compiling to remove the main class (to build a library for example)?
3. Version incompatibility?